The present invention relates to electrically operated valves and particularly valves employing a solenoid operator for effecting opening and closing of the valve in response to an electric signal provided to the solenoid.
Valves of the aforesaid type are often employed in control functions in fluid systems on motor vehicles because of the adaptability of the solenoid for operation by the relatively low voltage direct current power supply found on the vehicle. One such application is found in the control of the shifting clutch actuators in automatic speed change power transmissions employed in motor vehicle powertrains. In particular, with the advent and widespread usage of electronic controllers for controlling the transmission shifting, it has been found particularly suitable to employ solenoid operated valves for controlling flow of pressurized hydraulic fluid to the individual shifting clutch actuators.
Recent fuel economy demands and exhaust emission requirements have necessitated more accurate control of the shifting in vehicle automatic transmissions and have resulted in increased numbers of speed changes or gear sets for controlling the engine speed in a region of optimum torque output for minimal rate of fuel consumption. Electronically controlled automatic vehicle power transmissions have employed a plurality or bank of solenoid operated valves disposed on the manifold for distributing pressurized fluid to the various clutch actuator circuits in response to signals from electronic controller. In an effort to improve the torque transmission during speed changes it has been desired to provide a continuous signal analogous to the torque transmitted to the transmission output for enabling more precise controlling of the shifting clutches. Such a signal in the form of a pressure feedback signal analogous to torque is shown and described in co-pending applicant Ser. No. 10/327,792 filed Dec. 23, 2002 entitled “Closed Loop Control Of Shifting Clutch Actuators In An Automatic Speed Change Transmission”; and, the implementation of a pressure sensor for providing a pressure feedback signal in such devices is shown and described in co-pending application Ser. No. 10/165,950 filed Jun. 10, 2002, entitled “Electro-Hydraulic Controller For Automatic Transmission” and Ser. No. 10/401,408 filed Mar. 28, 2003, entitled “Electro-Hydraulic Manifold Assembly With Lead Frame Mounted Pressure Sensors”, which aforesaid co-pending applications are commonly owned by the assignee of the present application.
The aforesaid valve constructions for use in motor vehicle automatic power transmissions employ pressure sensors mounted either on the manifold or the electrical lead frame for enabling electrical connection to the solenoid operators for the individual valves However, this arrangement has proven relatively costly to manufacture, and difficult to assemble and install on the transmission during final assembly. Therefore, it has been desired to provided a simplified and low cost way or means of providing a fluid pressure output feedback signal for an electrically operated pressure control valve for a hydraulically operated system, such as the hydraulically operated shifting clutch actuators an automatic speed change power transmission for use in motor in motor vehicles.